1. Field of the Invention
The present invention relates to an acrylic copolymer elastomer, its blend rubber and a vulcanizable blend rubber composition, and more particularly to an acrylic copolymer elastomer blendable with a fluorine-containing elastomer, a blend rubber of the acrylic copolymer elastomer and a fluorine-containing elastomer, and a vulcanizable blend rubber composition.
2. Related Prior Art
Acrylic copolymer elastomers (acrylic rubber) have good oil resistance and heat resistance and are cheap, and thus have been widely used as vulcanization-molding materials such as automobile sealing materials, etc. Due to recent higher efficiency of automobile engines and consequent higher temperature in the use circumstances, materials of much higher heat-resistance are in demand.
Fluorine-containing elastomers (fluorine rubber), on the other hand, are used particularly at positions requiring a higher heat resistance among the automobile engine sealing materials owing to their distinguished heat resistance, but are very expensive. Furthermore, the fluorine rubber has such a disadvantage as a poor amine resistance, as compared with acrylic rubber. Various attempts, for example, formulation change, etc. have been so far made to improve the disadvantage, but no better amine resistance has been obtained yet. In the circumstances using an automobile engine oil containing an amine-based additive, there are fears of functional deterioration in the fluorine rubber product. Thus, the improvement of amine resistance is still keenly desired for the fluorine rubber.
In these situations, many attempts have been also made to blend acrylic rubber with fluorine rubber, thereby satisfying the required heat resistance and cost at the same time, but the conventional technique of cross-linking these two rubbers by a cocross-linking agent capable of cocross-linking these two rubbers can hardly satisfy even the intermediate heat resistance between the heat resistance of acrylic rubber and that of fluorine-containing, and no satisfactory amine resistance has been obtained yet.